3D-printable high torque servo/gear reduction

by Brian Brocken

This servo/gear reduction uses mostly 3D-printed parts. The servo uses a 775 36V 9000rpm brushed DC-motor which is driven by a BTS7960B motor driver which is controlled by an Arduino mega 2560. The stall torque of the servo is about 55kg/cm which is about 5.39 Nm. the peak current is about 18 amps when using a 6s LIPO battery (about 22-24V). the reduction ratio is 1:30.

For the intend of filming the internals of the servo for possible failures, the gears were printed in different colors and a 5mm acrylic lid was laser cut. Unfortunately I didn't get to film any awesome footage of gears exploding because they were far to strong. Even at a peak torque of 54kg/cm they didn't show the slightest form of flexing or cracks.

The two middle gears (blue and red one) use a stainless steel shaft of 6mm diameter. The holes of the gears are designed at 6.2mm diameter so they would fit nicely around the 6mm shaft but some additional filing/sanding might be required. The same might has to be done for the 20mm shaft holes.

A DXF file of the lid has been uploaded so people with a laser cutter can cut the lid out of transparent acrylic.

video: 


STL-files and the Fusion 360 source files can be downloaded here: https://bbprojects.technology/stl-fusion-360-source-files/3d-printable-high-torque-servo-gear-reduction-files

The Lid DXF file can be downloaded here

QUANTITY   COMPONENT NAME
1 × 775 Motor DC 12V-36V 3500-9000RPM Motor Large Torque High Power Motor link: https://www.banggood.com/custlink/DGvyjgpjip
1 × Arduino nano V3link: https://www.banggood.com/Geekcreit-ATmega328P-Nano-V3-Module-Improved-Version-With-USB-Cable-Development-Board-For-Arduino-p-933647.html?p=E01411629100201406T1&custlinkid=255135
1 × L298N motor driver link: https://www.banggood.com/Wholesale-Dual-H-Bridge-DC-Stepper-Motor-Drive-Controller-Board-Module-Arduino-L298N-p-42826.html?p=E01411629100201406T1&custlinkid=255131
1 × Heat shrinks link: https://www.banggood.com/328pcs-Heat-Shrink-Tubing-Insulation-Electrical-Shrinkable-Tube-Sleeve-Cable-21-p-1362019.html?p=E01411629100201406T1&custlinkid=669227
2 × stainless steel shaft dimensions: 6mm diameter, 70mm lenght
8 × 3D-printed parts Link to thingiverse: https://www.thingiverse.com/thing:3292860
2 × M5 bolt and nut dimension: 40mm lenght
1 × 20mm steel tube dimension: 125mm lenght
2 × screws 15mm lenght dimension: 4.5mm diameter, 15mm lenght
5 × screws 35mm lenght dimension: 4.5mm diameter, 35mm lenght

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